In the semiconductor manufacturing process, a pre-metal dielectric (PMD) liner layer is formed in order to prevent diffusion of the boron (B) and phosphorus (P) existing in the borophosphosilicate glass (BPSG), boron-silicate glass (BSG), and/or phosphorus silicate glass (PSG), etc., which are mainly used to protect an active area such as a source region and a drain region, and used as a PMD layer.
When a dangling bond exists on a surface of the active area of an image sensor, leakage current may be caused in the image sensor (e.g., in a photodiode which converts the light coming from the micro lens formed by photoresist to an electrical signal). In this case, the dangling bond can be removed by applying H2 annealing to the active area.
However, when an excessive amount of the H2 directly contacts the active area, the characteristics of the semiconductor device may be deteriorated.
On the other hand, when the H2 annealing is performed after the fabrication of the metal line, the H2 annealing becomes far less effective due to a substantial decrease in a probability of the H2 diffusion.